Variable speed-gear mechanism



Patented June" 16,1931

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vARiABLE SPEED-GEAR MECHANISM I Application filed January 6,1930; Serial No. 418,911, and in South Africa November 28, 1929.1

' The object of-the invention to provide an improved variable speed gear mechanism which will operate automatically under variations' in the load, and will be found particularly suitable for use in ,self propelled road'vehicles, mills and other machines for dealing with widely-fluctuating loads,- and the like. i

, "A speed-gear mechanism according to the invention comprises a driVing Shaft, a driven-shaft, a lay-shaft'geared to the driving-shaft and ,7 adapted to be geared to the driven-shaft ata plurality of various gearc ratios successively, and means uponthe layshaft adapted to operate" automatically to;

vary the'ratio at which it is geared to the driven-shafaaccording to the variations in the load applied to the latter. f

V Further, according to the inventionjthe ratio at which the lay-shaft driven-shaft is varied bythe operation of a member mounted-upon the former and caused to traverse the same'by, and proportion to, the load applied thereto.

One embodiment of;the invention, as ap-c plied to a variable gear mechanism for automobilesand the like, isillustrated diagrammatically in the accompanying drawings,

. whereof Fig. 1 isjwplan of the mechanism,

Fig.2 a section ofthe lay-shaftsleeveshowing the method of'its mounting 'uponthe lay-x shaft,;Fig. 3 a longitudinal section of the lay shaft sleeve showing the locating device thereof, and 'Fig. 4 is a. detail 'view' showingfthe free-wheel device of onset the driven-shaft pinion's. v v

1 Referring tothefdrawings, Jindicates the clutch-shaft of the vehicle, i. e., the driving 10a, 10b, and 100, of successively decreased diameter and mounted upon the sh'aft5 in proximity to said lay-shaft is'a, similar sleeve llg'also carrying "three gear-pinions is geared 1 to the 11a, 11b,'and 110, of successively increased diameter, the arrangement being such that as the lay-shaft sleeve is slid axially in the direction of the arrow against the pressure of a spring 12, the pinionslOa, 10b and 100 each engage inturn with the corresponding. pinions; 11a, 11?), or 110, thus.v transmitting the driving torque to the shaft 5. i In order that the sliding movement of saidlay-shaft 10 maybe controlled by the load upon, and therefore the resistance to rotation of, the shaft"5,ithepinion? (here ina'fter termed the lay-shaft pinion) is] splined helically' upon the lay-shaft, as; shown at 7a in such manner that, when r0; tate'd by the driving shaft pinion 6, the

load 'causesthe lay-shaft pinion? totrav-i erse the helical thread 7a, and by means of a sleeve-like distance piece 13 interposed between "the pinion 7 and the sleeve10, the}, latter may] be caused tofslide against "the pressure of theregul ating spring 12: Lock;

nuts 14: screwing upon the shaft '8 are .provided for the purpose ofadjusting thepressure of said spring 12 as reopuired, and the arrangement is such that for a maximum load (i."e., when 'theresistance to'rotatio'n of the shaft 5'is greatest) the lay-shaft pin-f ion 7 will traverse the thread 7 a to the utmost extent, when'the pinions 10b and 11c 1 will be engaged and the gear-ratio of the mechanism consequently reduced to a minimum. E; g. when starting thevehicle under load, the lowest gear-ratio 100, llqwill probably come into action.

As the "load gradually decreases, e. g.,as

the vehicle attains speed, or otherwise, the sleeve 10 is correspondingly forced back by the spring12 so as to bring a higher gearratio into operation, and whenthe load becomesa minimum, the pinions 10w and 11a are engaged, to produce theihi ghes't'gearratio," the pinion 7 being traversed along the thread 7 a to its initial position;

"lt'will be understoodthat the pinion 6 is made sufliciently wide to ensure its meshing with the pinion 7 at all points in the range of' axial movement of the latter.

The lay-shaft sleeve 10 is preferably keyed: upon the shaft 8 by means of'a Plu- 8id freewheel device maybe ions of the la fore so arranged that, in the sliding movev ment of the sleeve 10 to change gear, before the pinions 10a and 11a become disengaged, the adjacent pair 106V and 11b is partlally engaged, and similarly before the pinimisv 10b and 11b become disengaged the pair 10; and 110 is partially engaged, thus providing a oontinuous path for the driving toriflue and preventing the load from being re eased at any instant of the operation, In order to prevent the gear from jammin each of the pinions, 11b and 110 is provi ed witha free-wheel or ratchet device whereby the torque is always transmitted through the gears of higher ratio when. two alrs; are simultaneously engaged as, above, y reason of the fact that the sleeve ,11 is thus allowed to over-run the ratchet pinions 11b or 110. Conveniently, as illustrated in Fig. 4, in which the pinion 110 is shown formed of two concentric members 1110 and provided with inter-engaging sprin pressed awls 18.

1. or er to ensure thatthe various pin.-

.shaft sleeve 10 enter properly into.- mes with the cooperating pinions of'the sleeve 11, the sleeve 10 is provided with a locating device, as shown in Fig. 3., whereby it is constrained. to occupy one of the definite gear-positions by the action of a, pair of spring-pressed balls 19. mou t d within a slot 20 formed diam t r cally in the lay-shaft. 8, and co-acting with three circumferential grooves 21 provided upon. theinterior ofthe sleeve 10 so as to form abutments for said balls 19. 7

If des1red,an auxiliary non-automatic 7 forward gear may be provided, consisting of a separate pinion 22, fixed upon, the driving-shaft 4, engaging with an idler pinion 23 loosely mounted upon the lay-shaft 8 and a p1nion 24 keyed upon the drivenshaft, 5 adapted to beslid into engagement with said idler pinion 23 by meansv of a suitablehand lever (not shown); For-this purpose it is also necessary to provide the driven-shaft sleeve I 11 with means whereby it may he slid totally out of engagement, with. the lay-shaft, sleeve 10 Conveniently, the pinion is provided with a sleeveike ex en i 5 wh h, whe ai pin on 24 is engaged, abuts against the end of the slwYQ; '11 and moves-the, same endwise to h e ssary x nt- I this a e the sleeve 11 is, of course, keyed upon the shaft 5, preferably in a manner similar to that employed for the sleeve 10, as hereinbefore described.

Similarly, if it is desired to provide a hand-operated reverse gear, a pinion 26 having a sleeve-like extension 27, may be keyed upon the shaft 11 in such manner that, when slid upon said shaft to engage a reversegear pinion 28 provided upon the drivingshaft 4, all the remaining driven-shaft gears will be pushed well out of engagement. Preferably, a spring 29 is provided for the purpose of returning the sleeve 11 toits initial osition when either the auxiliary forward gear pinion or the reverse gear pinion is disengaged. 7

It will be understood that any numberof different gear-ratios may be provided by modifying the number of pinions upon the sleeves 10. and 11; indeed the more ratios there are, the smoother will be the operation of the device.

WhatI claim and desire tosecure by Letters Patent is I 1. An automatically variable speedear mechanism, comprisin a driving-shat t, a driven-shaft, a lay-shaft, means for gearing the lay-shaft to the driven-shaft at a plurality of various gear ratios successively, a pinion splined helically upon the la -shaft and geared to the driving-shaft, an gearchanging mechanism operable by the traversing movement of-said pinion upon the layshaft under variations in the load applied to the driven-shaft.

2. An automatically variable speedear mechanism, comprising a driving-she t, a driven-shaft, a lay-shaft, a pinion splined helically upon the lay-shaft and geared to the driving-shaft, a plurali't of gear-pinions fixed upon a sleeve slid ably mounted upon the lay-shaft, a corresponding plu-,

rality of gear-pinions carried by a sleeve keyed upon the driven-shaft and adapted to be engaged successively by the pinions of the lay-shaft sleeve as the latter is caused to slideby the traversing movementof the splined pinion, and a spring for controlling the movement of said lay-shaft sleeve.

3. An automatically variable speedear mechanism, comprisin a driving-sha a drivemshaft, a lay-shaft, geared to the driving-shaft, means for gearing the lay-shaft to the driven-shaft at a plurality of various gear-ratios successively, means uponthe laymechanism, comprising a driving shaft, a driven shaft, a lay shaft geared to the drivingshaft, means for gearing the lay shaft to the driven shaft at a plurality of various gear ratios successively, a pinion .splined helically upon the lay shaft, mechanism erable by the traversing movement of sald pinion upon the lay shaft under variations in the load applied to the driven shaft for automatically varying the ratio at which the lay shaft is geared to the latter, a reverse gear and a reverse pinion, and means for maintaining the remaining gears out of engagement vduring the engagement of said reverse gear.

In testimony whereof, I affix my signature.

MAXWELL L. F. VON BROEMBSEN'. 

